It is curtains for the northeast monsoon that spilled over to January. On Tuesday, the India Meteorological Department declared the end of the monsoon, which gave bountiful rains to the State and Puducherry during the first fortnight of January.
Officials said dry weather prevailed over the State on Tuesday except for very light rains over Tirunelveli. While light rains are possible over one or two places in south Tamil Nadu till Thursday, dry weather would set in over the rest of the State, Puducherry and Karaikal.
Such spillover of monsoon to January next year has been common in the past.
But what made this year’s spillover special was the copious rains it brought over all districts in January, considered a winter month.
Tamil Nadu has so far received 13.7 cm of rain, which is 935% excess than its monthly share of 13.3 mm till Tuesday. The percentage of deviation in rainfall ran in excess of even thousands for several districts such as Madurai, Chengalpattu, Tirunelveli and Tiruppur.
S. Balachandran, Deputy Director General of Meteorology, Chennai, said in the past two decades, there had been several instances where northeast monsoon extended up to the first fortnight of January. For instance, northeast monsoon ended on January 11 in 2001, on January 15 in 2017 and on January 18 in 2005, 2009 and 2013.
This year, easterly wave activity extensively triggered moisture convergence and brought widespread rain. Even easterly waves could bring torrential downpour than depressions or cyclones. Other global weather phenomenon like MJO (Madden-Julian Oscillation) that was in favourable position also influenced heavy rains.
The above normal Siberian High (a strong high atmospheric pressure area over Siberia) led to cold air surges over south China sea. Easterly waves generated over the south China sea were pushed towards the Bay of Bengal region, he said.
The weather station in Nungambakkam has recorded 16.6 cm rainfall so far this month.
The Meteorological Department forecasts that mist may occur over some areas of Chennai during morning hours and the maximum temperature would be around 30 degree Celsius till Thursday.
